Currently, there are various systems that monitor packets that are sent into and received from a network. These systems can identify characteristics of a packet sent into the network and then can identify any changes to the packet once it leaves the network. However, these systems break down in providing user friendly analysis to identify where changes occur within the network, especially when the network in controlled by another entity such as one or more service providers. This is because each service provider may route packets using different processes and may not provide the user with access to data within the service provider's network.
For example, many service provider networks will change the Differentiated Service Code Point (DSCP) markings (the Type of Service field in the Internet Protocol Packet Header) of packets entering the network to DSCP marking specific to the service provider (e.g., specific to a particular Quality of Service (QoS) for a packet type). Upon exiting the network, the service provider will set the DSCP markings back to the same value as when the packet entered the network. If the DSCP markings that the service provider are using in the network are for a lower Quality of Service than the Quality of Service required under a Service Level Agreement, current systems cannot detect this easily. If the DSCP markings for packets entering the network are different than the DSCP markings for the same packet leaving the network, existing systems may be able to identify that there is a problem; however they are unable to identify a specific node within the network that is causing the problem. This problem becomes worse when different markings are used for different packet types. Current systems may be unable to identify problems for different markings (e.g., markings for voice packets, data packets, audio packets, and the like).
Other systems, such as the system disclosed in U.S. Publication No. 2007/0086336, disclose a system that monitors packets sent into and returned from a service provider network using edge routers. The edge routers identify an application layer policy that is applied to the packets sent into and returned from the network. Metrics of the packets are generated and specific actions can be taken when specific metrics are detected. However, this system cannot detect specific nodes within the service provider network that may be the cause of routing packets at a Quality of Service that is less than provided in a Service Level Agreement. Moreover, this system cannot detect specific nodes within the service provider network that are changing fields in packets that may indicate a specific Quality of Service problem.